| 摘要 |
In an apparatus and method for diagnosing presence of absence of a (wire) breakage in electromagnetic coil means such as a duty ratio controlled solenoid or at least one exciting coil portion between an end of a stator coil and a tap of a stepping motor, a checking circuitry is connected to a junction between the electromagnetic coil means and a driving transistor (switching element) to provide a checking pulse signal which provides a particular level only when an input duty ratio (pulsewidth modulated) signal is at a predetermined non-actuation (low) level and no breakage in the electromagnetic coil means occurs. In the embodiment, the checking pulse signal is sampled at a predetermined sampling period which is shorter than the period of the pulsewidth modulated signal. A historical memory in a sub CPU records (stores) a history of the sampled checking pulse signal. The diagnosis of whether the breakage of the electromagnetic coil means is present or absent is carried out on the basis of the presence or absence of the history of the particular level (predetermined high level) in the stored content, the sampled checking pulse signal during a predetermined diagnosis delay time duration.
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